Recent advances in the manufacture and design of integrated circuits have enabled technology produces to provide portable instruments including palm-sized computers such as the Palm VII from Palm Computing, Inc. Santa Clara, Calif., personal digital assistants (PDAs) and the like. Accessories are available that allow a portable computer to become part of a telecommunications device. One such accessory is described in U.S. Pat. No. 5,606,594, granted to Register et al. on Feb. 25, 1997, entitled “Communication Accessory and Method of Telecommunicating for a PDA.” Similarly, U.S. Pat. No. 5,497,339, granted to Bernard et al. on Mar. 5, 1996 provides for a PDA that mounts within a communication device. A prior system describes an information appliance (PDA) and a network appliance (or telephone) that function independently as well as with each other as companion appliances.
In prior art, a communications appliance (digital telephone or Ethernet telephone) is connected directly to the Local Area Network (LAN), and the information appliance (computer or PDA) is connected directly to the communications appliance. That is, the communications appliance is always connected between the LAN and the information appliance (they are connected in series). Both system security means as well as types and method of data transmission are limited by the capabilities of the communications appliance (telephone). This topology limits the application to systems requiring Ethernet telephones or other specially adapted telephones. Thus prior art excludes applications which could possibly incorporate an existing public switched telephone network (PSTRN).
Prior attempts to solve PDA-based number portability and mobility problems, as well as problems of authentication, accounting and billing support for LAN telephones has been based on the use of calling cards, some of which require the user to recall a Personal Identification Number (PIN).